Magnetically actuated switches provide a compact, reliable and durable switching function. These switches offer a very slim profile, low weight and economical assembly and are used in an increasing number of applications in a variety of environments. They combine the tactile feel of a bulky mechanical switch with the compactness of a conventional membrane switch. Magnetically actuated switches of this general type are shown and described in U.S. Pat. Nos. 5,523,730, 5,666,096 and 5,867,082, the disclosures of which are incorporated herein by reference.
While magnetically actuated switches already have many applications, it is advantageous to expand the applications of such switches even further. For instance, it would be desirable to have magnetically actuated switches that can be adapted to any size or width while maintaining switch reliability. Sometimes switches require keys or activating surfaces that are large or wide compared to the force-applying member that actuates them. Common examples are the spacebar and shift and enter keys of a standard keyboard. Vending machines often have selection switches that are wider than users"" fingers or group of fingers. Machine controls commonly have large switches that are plainly visible and convenient because they do not require a precisely-located actuating force; hitting the cap or button anywhere on its surface will work. Switches of this nature, especially in the keyboard field, are sometimes referred to as multi-wide switches. Multi-wide switches have key caps, buttons or like activating members that are wide or large compared to either the underlying electrical contacts or a user""s fingers. The difficulty with multi-wide switches is transferring the actuating force from the key cap or button to the electrical contacts which may be substantially remote from the center of the actuating force. The moments generated by the offset actuating force can cause binding of the movable elements of the switch. Various arrangements are known for effecting smooth, non-binding movement of multi-wide actuators in standard electromechanical switches and in keyboards. These may include torsion bars, guide sleeves and the like. However, these solutions are typically not usable in magnetically actuated switches because magnetically actuated switches do not have the space available for such devices. While conventional devices may be adaptable to magnetically actuated switches, doing so would defeat one of the primary benefits of magnetically actuated switches, namely, their compact size. The present invention provides compact, reliable multi-wide actuators for magnetically actuated switches.
The present invention relates to magnetically actuated switches and is particularly concerned with a switch having a multi-wide actuator.
In one embodiment the switch of the present invention includes a substrate having a set of electrodes on the upper surface thereof. The electrodes include at least one pair of spaced contacts or pads. Electrical leads suitably connect the contacts to external electronics. The pads are arranged so that a conductive armature is movable into and out of engagement with the pads. Engagement of the armature with the pads will short them and cause switch closure. The armature is normally held in spaced relation to the contacts or pads by a coupler layer. The coupler layer is mounted above the surface of the substrate having the contacts or pads by a spacer. The spacer has an opening through it that surrounds the contacts. The armature is disposed in the opening. An aperture in the coupler layer is located above the armature so that an actuating force can be applied to the armature through the aperture. The coupler layer is a magnet. The armature is made of magnetic material. By magnetic material it is meant that the material is affected by a magnet. Conversely, non-magnetic material is material that is not affected by a magnet. The magnetic attraction between the coupler layer and the armature normally holds the armature spaced from the contacts or pads. An actuating force applied to the armature causes it to break away from the coupler layer with a crisp, tactile snap and move into engagement with the contacts, thereby closing the switch. In the present invention the actuating force is applied to the armature by an actuator. The actuator is typically a non-magnetic sheet overlying the aperture in the coupler layer. The actuator is engageable with the armature through the aperture. The actuator includes a force-receiving portion and a base portion. The base portion is always in contact with the coupler layer. The force-receiving portion is cantilevered from the base portion. When the switch is in its normal, unactuated condition the force-receiving portion is spaced from the coupler layer. The actuator may have a size that is large compared to the armature, to the contacts and to the size of a user""s finger. Application of actuating force to the force-receiving portion of the actuator causes it to pivot about the base portion. The actuator is sufficiently stiff such that regardless of where the actuating force is applied to the force-receiving portion, that force will be transferred to the armature, causing it to break free of the coupler layer and move into engagement with the contacts.
Another embodiment of the present invention has a substrate, contacts and a coupler layer similar to those described above. A multi-wide armature is used having a base portion and a force-receiving portion. The base portion always remains in contact with the substrate. The force receiving-portion is movable into and out of engagement with the contacts, and with the coupler layer. The force-receiving portion is exposed to an actuating force either by placing it beyond an edge of the coupler layer or in line with an aperture in the coupler layer. Application of actuating force to the force-receiving portion causes the armature to pivot about the base portion, carrying the force-receiving portion into engagement with the contacts. Removal of the actuating force allows the magnetic attraction of the coupler layer and armature to pull the force-receiving portion of the armature up and away from the contacts, thereby opening the switch.